Thanks - this turned out to be a problem of my own making. I'll pass it along in case anyone runs into the same issue.

I'm developing under Windows.

I built the libraw.dll library using the VC++ project included with the distribution.

The software that calls libraw.dll is developed using a different compiler. There appear to be some object size and alignment differences between them. As such, things in libraw_data_t weren't where the calling program expected them to be. Setting use_camera_wb from the calling program actually wrote the int to the wrong place.

I worked around this by writing some additional get and set functions so the data in a libraw_data_t need never be accessed directly by the calling program.

Thanks again for your help, and for a great library.

::Jack